1. Field of the Invention
The genus Trichogramma represents a vast array of endoparasitic species of minute wasps found in diverse habitats throughout the world. Their life cycle initiates with the adult female wasp ovipositing eggs into the eggs of a host insect. Hatching larvae feed on the host egg, pupate, and emerge within approximately 10 days of oviposition as mature adult parasites. These parasites are commercially reared and released in many countries for use as biological control agents against a plurality of agricultural pests, particularly those which attack economically important food and fiber crops.
All existing programs for mass rearing Trichogramma depend upon providing an ample supply of viable host eggs. As a result of the several handling steps and the requirement for fairly elaborate facilities, host egg production accounts for more than 90% of the rearing costs. It is envisioned that a substantial reduction in the overhead attributed to maintaining a host population would greatly enhance the role of Trichogramma in the control of agricultural pests. This invention relates to a cultivation method by which such a cost reduction can be realized.
2. Description of the Prior Art
The conventional procedure for propagating Trichogramma initiates with production and collection of an abundance of host eggs such as those of the Angoumois grain moth. The collected eggs are enchambered with a predetermined number of parasitized eggs so that the emerging wasps will infest the remainder of the lot. The infested eggs may either be refrigerated to retard hatching or else directly transferred to an incubation chamber for further development. Release of adult parasites typically occurs prior to or immediately after emergence. Because of the manual handling of both the host and the parasite, this procedure is unduly labor intensive and economically unfeasible.
Attempts to improve upon the conventional technique have centered upon optimization of conditions, automation, and implementation of a continuous flow principle from one stage to the next. For example, Andreev et al., U.S. Pat. No. 3,893,420 teaches a method wherein host eggs are collected by a pneumatic separator and are attached in symmetrical arrays on uniformly sized cards for subsequent transfer to each rearing station. While the method of Andreev et al. facilitates the production and handling of the eggs, it does little to offset the expense of concurrently rearing the host.